1. Field of the Invention
The present invention relates to a novel type Lactobacillus bacteria and, more particularly to novel Lactobacillus clearnas, Lactobacillus sulfurica and Lactobacillus nitrosus which are characterized by not having its growth accelerated by Na.sub.2 S.9H.sub.2 O and/or NH.sub.3, but instead reduces those two materials under specified conditions.
2. Development of the Invention
Conventionally known Lactobacilli are gram-positive, anaerobic or slightly aerobic, asporogenic rods and, depending upon the strain, Lactobacilli are in a cocci or bacilli form, curved form, coryneform, filiform, etc. They are non-motile, catalase-negative and do not reduce nitrates. Further, they do not decompose gelatin and do not produce indole or hydrogen sulfide. Some strains exhibit staining at their terminals. They have extremely weak proteolytic and lipolytic activity, grow well under an anaerobic or slightly aerobic condition rather than under an aerobic condition, are strongly saccharolytic, acid resistant, produce lactic acid in a yield of more than 50% by the fermentation of glucose and their growth is accelerated by the addition of acetic acid to the culture medium. They exhibit no pathogenicity to animals and plants.
It is also known that nutritional requirements of these bacteria are high, and they cannot grow unless a culture medium having a very high nutritional composition is used. That is, amino acids, peptides, nucleic acid derivatives, vitamins, salts, fatty acids or fatty acid esters and fermentable carbohydrates are required.
Classification of such Lactobacilli as to "species" has been heretofore evaluated by (a) saccharolysis, (b) gas production, (c) optical rotation, (d) growth temperature range and (e) growth pH range (Bergeys Manual of Determinative Bacteriology, 8th Edition, pages 576 to 578).
Among the aforesaid classification related items for evaluation, however, (e) growth pH range is variable to a certain extent, depending upon adaptability of the bacteria; and (c) optical rotation is an issue relating to commercial products rather than relating to in vivo characteristics. If one considers characterization items for evaluation relating to the intestine, oral cavity and vagina habitats of the bacteria, (a) saccharolysis is relevant only in relation to feed decomposition by the bacteria. Therefore, the relation of bacteria to its habitat and further to its function therein are not shown with a high correlation; the aforesaid bacterial classification is very distantly related to a classification based on the activities of the bacteria in a habitat filled with putrid substances, under an environment to prevent invasion of external enemies and where the order of 5.times.10.sup.8 cells/g survive. This inconsistency is now a cause for markedly restricting studies per se on Lactobacilli. This is because classification is a basis for developing a study protocol. In actuality, it has been desired that the conditions of the natural habitat of Lactobacilli be fully taken into account and bacterial classification be evaluated by mode of activity therein as early as possible.
For example, food orally administered is decomposed in the intestine and gradually absorbed in the living body on the one hand, and on the other hand, excreted via the course of putrefaction. The formation of putrid material is greatly dependent on enteric putrid bacteria. The putrid substance is also absorbed through blood vessels surrounding the intestinal tube and directly threatens the intestine and blood vessels in that area. For example, it has been reported that for repair of an intestinal tube injured due to ammonia produced in the intestinal tube, 4% of the energy in food is consumed (experiment using chickens).
It has been clarified by the present inventors that in directly correlating bacterial properties to materials present in the intestine, bacteria having a function of reducing enteric malignant materials such as H.sub.2 S or NH.sub.3 are considerably present in the Lactobacilli flora. This is an extremely important matter because effectiveness of the Lactobacilli has been actually proven on a material level, apart from a viewpoint of epidemiological or statistical studies. Further, speaking from a bacteriological standpoint, this discovery is influential in developing a fundamental solution to the inconsistency in conventional classification, strongly suggesting that criteria for classification be set forth quite different from conventional classification items. The two materials described above (NH.sub.3 and N.sub.2 S) are both not only representative of noxious materials in the intestine, but together with butyric acid are also alternatives for the various compounds containing sulfur atoms, nitrogen atoms and carbon atoms (Hereinfter referred to as S, N and C-compounds respectively) found in the intestine, as described in our Japanese Pat. Nos. 938,917 and 936,213.
As has been described before in detail, studies on the relationship between classification evaluation items of Lactobacilli and their habitat were insufficient in the past, with poor correlation as described above. As a new concept, however, introduction of Na.sub.2 S.9H.sub.2 O and NH.sub.3 as items of evaluation for classification of Lactobacilli has clarified that there is an extremely high correlation between bacterial properties and nomenclature of bacteria well known in the art, and the aforesaid two materials. That is, Lactobacilli can be classified into one of the groups below, based on their behavior to these materials.
(a) Group of bacteria which is found to be incapable of residing in the intestine--bacteria which are sensitive to Na.sub.2 S.9H.sub.2 O and NH.sub.3 and have no ability to reduce the levels of both of those materials.
(b) Group of bacteria such as acidophilus which have been said to be resident in the intestine--which are insensitive to Na.sub.2 S.9H.sub.2 O and NH.sub.3 but have no ability to reduce the levels of both of those materials.
The bacteria belonging to (a) and (b) described above are strains all isolated by senior researchers which are classified in points different from behavior to Na.sub.2 S.9H.sub.2 O and NH.sub.3. Separately, the present inventors have already clarified in Japanese Pat. Nos. 938,917 and 936,213 and Japanese Patent Application No. 134773/74 that there are present Lactobacilli which are poor in nutritional requirements and the growth of which is accelerated not only by lower fatty acids such as acetic acid but also by Na.sub.2 S.9H.sub.2 O and NH.sub.3, in a medium having poor nutritional composition.